Err30 on Canon 50D very often means the shutter assembly is defective. New genuine replacement shutter assembly will restore your camera to working condition!

With special adjustment software shutter count will be reset to ZERO. It's much helpful if you decide to resell the camera one day.

I can also carry out shutter calibration if pictures are complete dark at shutter speed 1/8000s (Something that happens after installing shutter!). This is a must for the task of replacing shutter assembly, otherwise your camera will end up unable to take good pictures at high speeds.